Grips or sabots are typically used in the launching or firing of sub-caliber, ballistic projectiles, which are projectiles having a diameter significantly less than the inner diameter of the gun bore through which the projectile is fired. Sabots are used in actual weapon systems, such as the armor piercing discarding sabot tank rounds (APDS). However, sabots also have a general application for test firings in order to launch both small scale and large scale projectiles from guns of bore diameter ranging from 5.56 mm. through 180 mm. The test firing of projectiles is an ongoing procedure for the purpose of obtaining experimental terminal ballistic performance data on such projectiles with respect to different arrangements and proportions of target orientation. Such testing requires the accurate measurement of the target cavity hole size plus a full examination of the characteristics of the target and target ejecta when perforation is achieved by the projectile.
Sabots, typically have been of three designs. The first design is a pull-type design where the projectile mass is carried rearwardly of the sabot. In such configuration, the projectile is pulled by the sabot from the gun bore by the expanding gases. The second design of a sabot is the pusher-type sabot wherein the projectile is carried forwardly of the sabot and is pushed from the gun bore by the action of the expanding gases upon the sabot. The third design is a push-pull type sabot, wherein the sabot is located at some point axially along the length of the projectile. The selection of any of the aforementioned methods of sabot for use with a given projectile is usually determined by the economic balance of the application and the production volume and tooling cost of the sabot. The pusher-type sabot from an economic standpoint is the most economical and is widely used for launching sub-caliber ballistic projectiles for test purposes.
Previous designs of pusher-type sabots have employed a homogeneous steel pusher plate positioned behind the projectile. The homogeneous pusher plate absorbs the forces associated with the initial movement of the assembly in the gun barrel by the expanding gases and thus pushes the projectile from the gun bore. A drawback of the homogeneous pusher plates of the type typically used is that when the projectile and pusher plate exit from the gun bore, the pusher plate, while separating from the projectile, in many instances would follow the projectile to the target and impact the target proximate to the penetration made by the projectile. When this occurs, the value of the test is obviusly negated since the terminal ballistic performance data, including the target cavity and hole size, and characteristics of target ejecta are distorted as a result of the sabot contacting the target.